Simplify the following expression: $q = \dfrac{r}{6} + \dfrac{r}{4}$
Explanation: In order to add expressions, they must have a common denominator. The smallest common denominator is the least common multiple of $6$ and $4$ $\lcm(6, 4) = 12$ $ q = \dfrac{2}{2} \cdot \dfrac{r}{6} + \dfrac{3}{3} \cdot \dfrac{r}{4} $ $q = \dfrac{2r}{12} + \dfrac{3r}{12}$ $q = \dfrac{2r +3r}{12}$ $q = \dfrac{5r}{12}$